Theater mode caused lag. This has been established for quite some time now. Lag is the biggest problem of COD for the past 4 iterations. Dedicated servers will go a long way to reducing lag dramatically enough to bring "fun" back into COD.

The thing I want improved is the physics when killing an enemy. If I shoot someone 4 times as they are falling down (straight after the kill) then the body should still react to the shots. Would love to see this added as the initial animation(s) when the kill happens relates the vast majority of times to where you hit the enemy. They need to take it one step further.

take extinction and add it to multi-player. Imagine team death match and aliens/zombies come out and attack both teams. Yeah, shooting each other gets old after all the years of COD games.....It would be nice to watch your back from other players and even funner to see your enemy get swarmed LOL.